This application is based upon application No. 2000-288723 filed in Japan, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an image shake preventing mechanism and an optical device provided with the mechanism. More specifically, the present invention relates to the mechanism for preventing an image shake, or for correcting or compensating a deviation of an image-forming position, which is caused by shaking or moving of a body provided with the mechanism, and relates to the optical device, for example, a pair of binocular, a camera, and so on, provided with the mechanism.
2. Description of the Related Art
Conventionally, there have been proposed some mechanisms for preventing an image shake of an optical device. For example, the mechanisms, in which a correcting or compensating optical system is driven, are classified into a type with an apex angle changeable prism, and another type with a translation lens. Regarding most of the mechanisms belonging to the latter type, the lens is driven by means of thrust drive using an oscillating coil, or lever drive using a motor.
In the thrust drive, friction against a guide rod increases necessarily, and it acts as a load with respect to servo control. In the lever drive, although frictional load decreases, reversing the drive direction causes delay due to some play of lever connecting portions, and it acts as a load with respect to servo control.
With any kinds of drive souses, lighter mass of a driven body makes response faster and resonance frequency higher, and thereby makes servo control easier. However, in conventional mechanisms for preventing an image shake, the holding mechanism for movably holding the correcting or compensating lens tends to become large.
Especially, binoculars provided with the mechanism for preventing an image shake, necessarily become large, because a pair of correcting or compensating optical systems must be driven synchronously.
Accordingly, it is an object of the present invention to provide an image shake preventing mechanism for preventing an image shake, the volume and mass of which are minimized.
It is another object of the present invention to provide an optical device for preventing an image shake, which volume and mass are minimized.
In order to achieve the above objects, according to one aspect of the present invention, there is provided an image shake preventing mechanism, comprising: a driven member to be driven so as to prevent the image shake; a holding member for holding the driven member; a first parallel linkage member arranged perpendicular to an optical axis of the driven member, the first parallel linkage member having link parts arranged in a form of parallelogram and connected with each other by flexible parts so that the first parallel linkage member can be deformed into any other form of parallelogram in a plane perpendicular to the optical axis of the driven member one of the link parts being fixed to the holding member; an intermediate member fixed to another of the link parts of the first parallel linkage member parallel to the one thereof; a second parallel linkage member overlapped with the first parallel linkage member in parallel relation thereto, the second parallel linkage member having link parts arranged in a form of parallelogram and connected with each other by flexible parts so that the second parallel linkage member can be deformed into any other form of parallelogram in a plane perpendicular to the optical axis of the driven member , one of the link parts being fixed to the intermediate member; and a base member fixed to another of the link parts of the second parallel linkage member parallel to the one thereof, wherein the one of the link parts of the first parallel linkage member is generally perpendicular to the one of the link parts of the second parallel linkage member.
In the construction, the driven member is driven in a first direction perpendicular to the optical axis of the driven member, when the one of the link parts of the first parallel linkage member moves relative to the anther thereof. The driven member moves in a second direction perpendicular to the optical axis of the driven member, when the one of the link parts of the second parallel linkage member moves relative to the another thereof. As the one of the link parts of the first parallel linkage member is generally perpendicular to the one of the link parts of the second parallel linkage member, the driven member can be driven relative to the base member in two directions generally perpendicular to each other. For example, by means of moving the holding member and/or the intermediate member relative to the base member, the driven member can be driven.
In the construction, the holding member, the first parallel linkage member, the intermediate member, the second parallel linkage member, and the base member can be formed integral with each other, so that the image shake preventing mechanism is unitized. Moreover, it is possible to minimize the total dimensions of the image shake preventing mechanism, by means of disposing the holding member, the first parallel linkage member, the intermediate member, the second parallel linkage member, and the base member in a direction perpendicular to a direction of moving the driven member, in substantially overlapping relation with each other. Additionally, a member or a part between adjacent members or parts is not necessary to be rigid in a direction perpendicular a direction of moving the driven member, and therefor can be made thin.
Accordingly, volume and mass of the image shake preventing mechanism can be minimized.
In order to achieve the above objects, according to another aspect of the present invention, there is provided an optical device, comprising: a driven member to be driven so as to prevent the image shake; a holding member for holding the driven member; a first parallel linkage member arranged perpendicular to an optical axis of the driven member, the first parallel linkage member having link parts arranged in a form of parallelogram and connected with each other by flexible parts so that the first parallel linkage member can be deformed into any other form of parallelogram in a plane perpendicular to the optical axis of the driven member , one of the link parts being fixed to the holding member; an intermediate member fixed to another of the link parts of the first parallel linkage member parallel to the one thereof; a second parallel linkage member overlapped with the first parallel linkage member in parallel relation thereto, the second parallel linkage member having link parts arranged in a form of parallelogram and connected with each other by flexible parts so that the second parallel linkage member can be deformed into any other form of parallelogram in a plane perpendicular to the optical axis of the driven member, one of the link parts being fixed to the intermediate member; and a base member fixed to another of the link parts of the second parallel linkage member parallel to the one thereof, wherein the one of the link parts of the first parallel linkage member is generally perpendicular to the one of the link parts of the second parallel linkage member.
In the construction, the driven member is driven in a first direction perpendicular to the optical axis of the driven member, when the one of the link parts of the first parallel linkage member moves relative to the anther thereof. The driven member moves in a second direction perpendicular to the optical axis of the driven member, when the one of the link parts of the second parallel linkage member moves relative to the another thereof. As the one of the link parts of the first parallel linkage member is generally perpendicular to the one of the link parts of the second parallel linkage member, the driven member can be driven relative to the base member in two directions generally perpendicular to each other. For example, by means of moving the holding member and/or the intermediate member relative to the base member, the driven member can be driven.
In the construction, the holding member, the first parallel linkage member, the intermediate member, the second parallel linkage member, and the base member can be formed integral with each other, so that the image shake preventing mechanism is unitized. Moreover, it is possible to minimize the total dimensions of the image shake preventing mechanism, by means of disposing the holding member, the first parallel linkage member, the intermediate member, the second parallel linkage member, and the base member in a direction perpendicular to a direction of moving the driven member, in substantially overlapping relation with each other. Additionally, a member or a part between adjacent members or parts is not necessary to be rigid in a direction perpendicular a direction of moving the driven member, and therefor can be made thin.
Accordingly, volume and mass of the optical device can be minimized.